Dave,
First, nocks for most carbon shafts now days are only pressed in and not glued in. Needle nosed pliars, leatherman, etc. will pull them out though sometimes a slight twisting will help.
I always tune by cutting off the nock end a bit at a time. I start by putting as much insert and point weight I think will be appropriate and bare shaft after that. If you really want to remove the insert without glueing it in I believe some guys have used plastic wrap or even teflon pipe tape.